"Peter Clark" wrote:


Perhaps to complete my reasoning - the original post says it drifts
off altitude when in level flight clicking ALT.

Sorry, that was incorrect. If ALT is selected in level flight, it will hold.
Altitude capture is the only thing not working.


AFAIK the only time
the KAP140 cares about the altimeter setting and the preselected
altitude is when it's in a capture mode, and it uses it's internal
pressure transducer to maintain altitude. Course, wouldn't be the
first time I've been wrong about the internal workings of the box, but
it's really not that big a deal to replace it and see - it's not like
there's no known history of the KAP140 computers being problematic...

The KAP 140 has been swapped for a known good one. No joy.

The wiring has been checked for a ground on the Gray code lines & found to be
ok.

The tech has plugged a laptop into the system and sent various coded
altitudes to the KAP 140 and it has decoded them correctly.

Thanks a bunch for your input.

--
Dan
T-182T at BFM